ATM switching facilities are typically used by telecommunications providers for data transport, but are being used more frequently to carry bearer traffic associated with telephone calls between switches in the Public Switched Telephone Network (PSTN). The deployment in the PSTN of interfaces to ATM facilities permits ATM facility providers to broaden their customer base, thus improving return on their investment in ATM network infrastructure. ATM facilities enable greater flexibility in call routing, since ATM routing is not restricted by the hierarchical structure that governs call routing in the present day PSTN. In addition, ATM facilities can be owned and operated at relatively lower costs than conventional TDM facilities. ATM switches also have a smaller footprint than TDM switches, so the physical plant is less costly to maintain.
One way in which PSTN switches can be arranged to use an ATM backbone network for inter-switch call completion is described in applicant's co-pending United States patent application entitled TRANSIT TRUNK SUBNETWORK SYSTEM which was filed on 23 Sep. 1998 and assigned Ser. No. 09/158,855, the disclosure of which is incorporated herein by reference. The transit trunk subnetwork includes interfaces between TDM switches and the ATM backbone network, referred to as Multi-Service Platforms (MSPs). The MSPs convert pulse code modulated (PCM) data to ATM cells and vice versa. The MSPs also map TDM trunks to ATM Virtual Channel Connections (VCCs) so that bearer traffic can be transferred through the ATM backbone network between TDM switches in the transit trunk subnetwork.
The transit trunk subnetwork is being implemented as a solution for traffic congestion in the PSTN because it enables traffic to be routed through the ATM backbone network between TDM switches in a transit trunk subnetwork. The transit trunk subnetwork also enables dynamic bandwidth management by controlling VCC allocations on a responsive or a predictive basis to ensure efficient use of bearer traffic facilities. The facilities in the ATM backbone network are therefore reserved only in proportion to demand so that other functions, such as the transfer of data from other networks, may use excess capacity in the network.
ATM facility providers are also experiencing demand for access to ATM facilities by competitive local exchange carriers (CLECs). Since ATM facilities offer lower cost transport for the bearer traffic associated with telephone calls, CLECs regard ATM facilities as a viable alternative for reducing their operating costs to enable more competitive service offerings. Under recent telecommunications regulations implemented the United States, an incumbent local exchange carrier (ILEC) must permit a CLEC to lease access to facilities which are owned and operated by the ILEC for the purpose of providing local service to interested customers. Under such mandated arrangements, the CLEC incurs recurring charges for access to ILEC facilities. Those charges result in lower net operating margins for CLECs. There therefore exists an interest in equipment that is adapted to most simply and inexpensively integrate PSTN switches with an ATM backbone network.
Accordingly, a need exists for an apparatus which reduces the number of components required to interface TDM switches with an ATM backbone network so that the capital investment in such equipment is reduced. A need also exists for an apparatus that permits ATM interfaces to be integrated into the physical plant of a TDM switch so as to reduce the footprint of such systems. Such an integration of facilities substantially reduces the floor space required and, consequently, operating overhead.